Problem 2.185

A saturated water vapour is contained in a cylindrical vessel under a weightless piston at a temperature \(t=100^{\circ} \mathrm{C}\). As a result of a slow introduction of the piston a small fraction of the vapour \(\Delta m=0.70 \mathrm{~g}\) gets condensed. What amount of work was performed over the gas? The vapour is assumed to be ideal, the volume of the liquid is to be neglected